Erratic BKO Velocity. Advice?

I'm trying to dial in the velocity on my new BKO, but can't get it to remain stable. The velocity jumps between 190 fps and 310 fps, and often the marker won't even cycle. There are times when the velocity will remain within +/- 20 fps for 4 or 5 shots.

Even the smallest adjustement to the LPR can result in 100 fps changes, but other times it takes 3/4 of a turn to get even 20 fps changes.

I called ICD looking for help but didn't find any there. They told me to adjust the HPR to 200 psi, back the LPR to the point that the marker would stop cycling, then re-adjust the LPR to the desired velocity. I tried exactly that with the same results.

I noticed 2 of the members in this forum had BKOs with holes in the micro line from the factory. I checked my line but couldn't find any leaks, although there is a thin, weak spot where the line fits over the LPR adapter. The spot isn't leaking right now, but I'll keep my eye and ear on it.

A few facts: I'm using a 68 ci 4500 psi Crossfire tank with 450 psi output and have installed the standard macroline and fittings provided with the marker. When I screw in the tank the HPR gauge spikes to 300 psi (the highest reading) and then backs down to 200 psi after 5 clearing shots.

Dial out your LPR until it won't cycle. Then crank it up until you hear the solenoid vent. Fire a couple shots while SLOWLY backing out the LPR until it quits venting. then just leave the LPR there. Adjust your velocity by the HPR at the chrony.

Goldie: Thanks for the tips. I tried exactly what you listed and got the consistency to about +/- 10 fps at 250 fps (indoor field's limit). There were occasional +/- 15 fps outliers, though. When I dialed the marker for 280 fps (outdoor field's limit) it was actually more consistent, about +/- 3 fps. Any ideas why the marker is less consistent at lower velocities?

ditangquan: I'll call ICD and order a new line on Monday. The Autococker pneumatic line at my local shops is actually a little thinner than the line in the BKO. I'll have ICD give me an exact replacement.

mike da bushman: No leaks in the macro line, just a weak spot in the internal micro line. How loud would a pin hole be in the micro line?

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I don't think there is 200psi running through that line....shouldn't there only be 200 or so psi going from the HPR to the LPR and then from the LPR ------micro line is here (oops, i said macro before)-----> solenoid should only be around 90psi...... so I'd say less than 100psi for sure....anyone else?

you know what i'm mistaken there is more if he's using a preset tank, if so theres 850 psi going through the macro line then when it hits the hpr it brings it down to whatever pressure the marker is set at............

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I'm running a preset 450 psi output Crossfire tank. So, the mAcroline has 450 psi running through it, but the HPR takes it down to 200 psi and the LPR takes it to about 85 psi. The mIcroline should only have about 85 psi if I understand the internal workings right.

I called ICD one more time and worked my way through to one of the more experienced techs. Here's what he recommended:
1. Set the HPR to 200 psi.
2. Adjust the LPR up until it leaks.
3. Back the LPR down 1 FULL turn. The marker should be shooting at around 270 fps.
4. Adjust both the HPR and LPR in small (VERY small) incremements until the right velocity is reached.

My local indoor field has a max fps of 250. Using this method I was able to keep the velocity within +/- 3 fps of 245 fps. Pretty good. My HPR wound up at around 180 psi.

Wrong. That's not what Goldie said. If you read his post, he said to back the LPR until it stops venting, NOT back out a full turn after venting has stopped as ICD recommended. Goldie also said to leave the LPR set at the point where it stops venting and adjust the HPR, instead of ICDs advice of slowly backing down the LPR and HPR at the same time.

Goldie's advice worked great for around 275 fps, but still resulted in erratic velocities below that.

I totally appreciate Goldie's input, he's obviously a well informed Bushmaster owner. But his advice was different than ICDs.

Not that I'm wanting to argue, but I think using the LPR and HPR to adjust pressure is not right at all.

First off, the ram takes a certain pressure to open the valve reliably every time. The HPR setting has very little to do with how much pressure the valve needs to be opened with. Just because you lower your HPR pressure doesn't mean you need to lower your LPR with it. As long as you stay on the high end of the LPR settings you will be alright. But if you start backing it out and lowering the pressure, there's going to be more of a chance for inconsistency.

Second of all, the bushy, angel, tribal, etc, all use the same basic setup as the BKO. And I've never seen ANY of them recommend using the LPR to adjust velocity.

Third, having to make 2 adjustments on 2 seperate regs with no gauge (ok one has a gauge) is WAY to complicated for the target audience of this marker.

I agree. The velocity adjustment is way too confusing for the target audience, especially considering everyone has a different opinion, even within ICD.

Some of the ICD techs say to use the LPR ONLY for adjusting the velocity. The BKO manual states, in bold, "The low pressure regulator is your main source for paintball velocity adjustments." Another ICD tech said to use BOTH the HPR and LPR. You're advice is to only use the HPR.

What's a new BKO owner to do? I imagine many BKO owners will be upgrading from blow back markers where they just turn a single screw to adjust the velocity, or will be new marker owners all together. This "discovery" process for adjusting the BKO is going to be confusing and frustrating.

Well, for me, the combo HPR/LPR adjustment worked well for the 250 fps range. This weekend I'll play at an outdoor field with a 280 fps limit, so I'll have to experiment again.

Hopefully ICD will settle on effective adjustment method (NOT adjusting the LPR only, in my experience), and publish that in their manual.